Medical preparation consisting of disodium calcium chelate of ethylene diamine tetraacetic acid



United States Patent MEDICAL :PREPARATION CONSISTINGR OF-I' D IS OY-DIUM YCALGIUM: CHELATE 1 OFi-ETHYLENE =:DI-' 5 TE'I RAACETIC.ACID

FfedrickC. 'B'ersworth, Verona; N. J and MartimRi'ib'in; Silzg.Spring,,.-Md.;..said-.Rubin. assignor .tousaid-iBers wo T 1 No Drawing;ApplicatiomMarcifi 17; 1951; Se'rial' Noz; 216,258

This invention. relates'to med-icine and moreparticularly'toialichem-ical compound w-hich -is suitablet-for, use{)mheremovalof toxic metal compounds-fromthe human Morecparticul'arlythe objectof the-invention is to; 20 provide. a non-toxic base 1exchange "chemical 1 compound 1 which maybe introduced-into thebloodstrearn and which by base exchange reactionwith toxi'c base and raremetal ions present. inrthe bodywv-ill remove the toxic metals in theform ofi 'an'excretable non=toxic compound; l

Still another objecti is to provide i an I organo-metalli'c complexcompound which is; 1 per se, non-toxic if to the humanw -system andwhich may be tolerated in relatively large: amounts :which' compoundriscapable of basei ex change reaction with toxic metal ions in thehumansylstcm. to: remove same as =nontoxic excretable soluble sa ts;

Other'objects will -be apparent as'fithe invention is more fullyhereinafter disclosed.

In accordance with these objects we' -have di'scovered that'calciumiethylene diamine tetraacetic acid disodium salt? is as nontoxic-'-organo-metallic compoundawhich is' toleratedin the human'systemin relatively large amounts and that this compound reacts as a baseexchange compound: lwith a largee number of 1 heavy I metal and" rare 40metal ions in aqueous solutions to convert same into solwv bleorgano-metallic complexes with liberation of nontoxic calciurri ions andthat when this said calcium complex is introduced intotthec-blood streamin pyrogen-free isotonic solution the said calcium salt efiectively andrelatively rapidlyremoves said toxic metal ions from the-body s stem.

In accordance with these discoveries the invention consists in the'i useandapplicatiomofinomtoxic calcium-ethylene.diaminettetraaceticacid.disodium-salt in the hurnan body: fort baseexchange wreactionawithf toxic metalt ions to solubilize saidionsasnon-toxic complexes for excretion removal from the body.

GaI'ciumLethyIene diamine tetraacetic acid tiisodium salt is anorgano-metallic complex to which iis generall y ascribed thetfdllowing.'structuralaformula :1

0112-0 0 ONa GHQ-C o ONa N: CH:- CH: N

HT 05 H,

This salt in aqueous solution has a pH approximately 7.4 and in aqueoussolution has the unexpected chemical property of reacting as a baseexchange compound with most of the other metal ions liberating the Caion and forming water soluble complexes with the other metal ions thatare, per se, non-toxic. In this reaction the calcium ion held in complexcombination in the compound appears, contrary to expectation, to berelatively weakly complexed and to be capable of being displaced by suchweakly basic metals as lead and tin. So far as we now know magnesium isabout the only metal that is above calcium in the displacement series ofmetals in this complex compound.

Accordingly, in the treatment of cases of metal lon poisoning, such aslead poisoning for example, the introduction of this calcium complexinto the blood stream intravenously or by sub-cutaneous injection, byskin "ice absorption or: by ingestion; is =hi'ghly' effective 'inremovingsthe.poisoning metal tion from the system asan inert chelatecompl'ex which is soluble :in the blood stream and" excretable fromtdhe:body a'lOl'lg -iwltl'lii excess amountsof theicalcium'complex;

The base .9 exchange. reaction is relatively simpleand understandable;In-1'the caseof di-valentmetalions" the polysvalent metal 2 ion.changei: reaction? is rnonoi-molecular.

lar. Thorium, uranium, vanadium-and-simi1ar polyval'ent metals requiretwo or more molecules 0f -the cal cium complex for base exchangereaction.=-

The use and application: of this calcium complex medic inallyrequires-.first-a: chemical-1y pure: compound.- This e compound may beformedby. dissolving ethylene d-iamine tetraacetic": acid',= whichhasbeen repeatedly precipitated from water 310 remove therefrom allwater soluble impurities;rin a-pyrogen-free aqueous solution containingchema ically purer-sodium. hydroxlde' in. an amount providing.

tw0 =(2) molar-weights ofzthehydroxide for each molar weight of theacids This reaction-:will :occur inthe-cold" but llS' better. and morerapidt with agitation and:- gentle heating.

To :ithis 'ssolution is added-one molar weight of calciumionsfperumolar.tweight of the acid :either in the form of .aisolublesaltssuch.aszthe ch1or-ide-or:acetate'or as aninsoluble basic compoundsuch ias the oxide, hydroxide or: carbonate;:. and: thewsolution isagitated with heating un'tiliis'olutionlis'icomplete.

The-solution is 'then concentrated by: distilling oft 'the wateriofS0lut10l1 t0-'a determlned desired concentration penzunitofrvolumeand-the pH of the solution is adjusted by appropriate additions 1 of;acid; or alkali to F a pH of about'.l7.2-.- to v7.4. A'cid additionsmayzinclude-hydro chloric; acid on one 'ofi the non-toxic organic acids suchas aceticiacid. ODYCltIlC 'aCld. Alkali" additions may:be

sodium, potassiumnor. ammonium hydroxide ora basic non-toxic:am1ne,-:.sucha as :tnethanolamlne.

In'irplace. of. thea sodrum salt 1n-th1s calc1um complex 5either'npotassium,-ammonium or: non-toxic amine salts mayub'e..substitutcd: without essential departure from the invention sand with.substantially: equivalent result's and 1 thewtermwsodiumwasitzmayqherei'nafter appear is meant to. -includer' such equivalent:subs'tituents.-

.In:the.use= and application of this pyrogen-free solutionofuthe.c'alcium: complex for; the purposes ofthe 1 present invention, thesolution may be takenr internally, or injected sub-cutaneously; orincorporated in -an.-isotonic solution for-iintravenous -injectionaor itmaybe incorporated 'intoan :absorbablegrease 'or oil for absorptionthroughthe" :skin into the bodyifluids.-

Experiments: have :demonstrated that the tolerance amount of thiscalcium complex in the body is quite high and that the calcium contentof the complex does not afiect the system except and unless it isdisplaced from complex combination by base exchange reaction with othermetal ions present. As all metal ion chelate compounds of this aminoacid are highly soluble and are rapidly excreted from the system withbody fluid a temporary excess of the calcium chelate is not injurious tothe system.

As typical examples of the present invention the following examples aregiven by way of example but not by way of limitation:

Example 1.--Intraven0us.-A slurry of 29.2 g. of ethylene diamine tetraacetate in ml. of pyrogen-free distilled water was mixed with a solutionof 8.0 g. of sodium hydroxide in 50 ml. of pyrogen-free distilled water.The acid dissolved readily on stirring and gentle warming. To thissolution was added a solution of 11.1 g. of anhydrous calcium chloridein pyrogen-free distilled water. The pH of the solution was adjusted to7.4 by the addition of sodium hydroxide solution and the final mixturemade up to 1000 ml.

To a group of rabbits previously posioned by intraperitioneal injectionof a solution of lead acetate was Patented Jan. 4, 1955 given a seriesof injections of this calcium disodium ethylene diamine tetra acetate byvein in dosage of 200 mg./kg. The amount of lead excreted in the urinewas then determined and compared to a similar group of animals that hadnot been treated with this preparation. It was found that the treatedanimals showed approximately a 1000% increase in the quantity ofexcreted lead. Further in contrast to the control group it wasdemonstrated that the appearance of the lead in the urines was veryrapid in the treated animals.

In a similar experiment a group of rates were poisoned by theadministration of nickel salts. Treatment with the solution of calciumcomplex described above again showed a prompt excretion of the poisonousmetal. In this case the recognition of the excreted nickel salts wasfacilitated by the appearance in the urine of the deep blue color of thenickel ethylene diamine tetra acetate complex.

Example 2.Subcutaneus.The disodium calcium ethylene diamine tetraacetate solution was prepared as described above but for purposes ofsubcutaneous administration higher concentrations of the activeingredient being permissible, the final volume was adjusted to 500 ml. Adosage of this solution equivalent to 500 mg./ kg. of the therapeuticagent were given to groups of animals as described in the experimentabove. The elimination in the urine of posionous metals as lead andnickel could be demonstrated in the same manner as described above. Inthe case of subcutaneous administration the onset of the elimination wasdelayed for a period of up to eight hours compared to the immediateresults with the intraveous administration above.

Example 3.Ingesti0n.For oral application the disodium calcium ethylenediamine solution described above was concentrated to dryness in vacuo.The white solid so obtained showed the correct elementary analysis forcalcium, sodium, carbon, hydrogen and nitrogen. For oral use it could beincorporated into a tablet containing dextrose as the excipient or intogelatin capsules. In the manner described above several groups of ratswere poisoned by administration of nickel or lead salts. The calciumcompound was then incorporated into the animal food in a concentrationof 3% of the active ingredients. Over a period of several days a markedoutput of poisonous metal occurred compared to the control animals.

Example 4.Ointment.-The sodium calcium ethylene diamine tetra acetatedescribed in Example 1 was made up to a final volume of 200 ml. inwater. This solution was blended into one pound of a water miscibleointment base to give a smooth creamy emulsion containing approximately5% of the active ingredient. Daily skin application over a period of twoweeks of this ointment to metal poisoned rats resulted in a markedexcretion of the metal poison from the body of the animal into theurine. The amount of the chelate compound in this emulsion may be widelyvaried without essential departture from the invention from a very smallamount approximating 1% to a large amount approximating 20%. Theselection of 5% in the example given is by way of illustration and notby way of limitation.

Example 5.-A solution of the disodium calcium ethylene diaminetetraacetic acid salt or chelate compound of the above composition wasadministered to a patient with heavy metal poisoning by the intravenousroute. The patient was given 5 grams of the disodium calcium ethylenediamine tetraacetic acid salt or chelate compound in this form daily fora period of three weeks, and 10 grams daily for a period of one week.There were no untoward eifects of the medication. The blood pressure,kidney function, liver function and metabolic activity all remainednormal. Analysis of the urinary excretion proved a substantiallyincreased excretion of the metal poison.

In substitution for ethylene diamine tetraacetic acid in the above Na-Cacomplex we may use a plurality of other polyamino poly acetic acidswhich are generally classified as unnatural synthetic polyamino polyacetic acids which are not metabolizable and the chelates of which aresimilar chemically to those of the Na-Ca chelate compound of ethylenediamine tetraacetic acid. Typical of these substituent polyaminopolyacetic acids are 1,2 cyclohexyl diamine n,n' tetraacetic acid,diethyl ether b,b' diamino n,n tetraacetic acid, ethylene glycol 1,2ethylene ether omega,omega diamino n,n tetraacetic acid, trimethylenediamino tetraacetic acid, propylene diamine tetraacetic acid, andothers, and where the term ethylene diamine hereinafter is used in theclaims it is meant to include these equivalent substituent acids.

From the above disclosure and examples given it is believed apparentthat the calcium chelate compound of the present invention isexceedingly effective in the removal of toxic metal ions from the bodysystem and that its manner of use and concentration employed may bewidely varied without essential departure from the present invention.

In view thereof all such modifications and adaptations of the calciumchelate in this new field of utility are contemplated as may fall withinthe scope of the following claims.

What we claim is:

l. A medical preparation consisting of a pyrogen-free aqueous solutionof the disodium calcium chelate compgu7ng of ethylene diaminetetraacetic acid having a pH 0 2. A medical preparation consisting ofthe dehydrated pyrogen-free solution of claim 1.

References Cited in the file of this patent UNITED STATES PATENTS2,461,519 Bersworth Feb. 15, 1949 FOREIGN PATENTS 431,375 Great BritainJuly 5, 1935 245,126 Switzerland Oct. 31, 1946 262,670 Switzerland Oct.1, 1949 OTHER REFERENCES Kissin et al.; Science, vol. 112, page 367(1950), September 29, 1950. Albright: J. A. M. A., vol. 13, pp.2049-2053 (1939).

1. A MEDICAL PREPARATION CONSISTING OF A PYROGEN-FREE AQUEOUS SOLUTION OF THE DISODIUM CALCIUM CHELATE COMPOUND OF ETHYLENE DIAMINE TETRAACETIC ACID HAVING A PH OF 7.4. 